Retrievable self-decentralized hydra-jet tool

ABSTRACT

A retrievable self-decentralized hydra-jet tool for jet treating the face of a formation penetrated by a well bore. The tool is adapted to be dropped or lowered by a wire line through a tubing string in the well bore to seat in a seating nipple at the lower end of a tubing string and to be retrieved from the tubing string by a wire line or the like after a jet treating operation. The tool includes a jet treating head assembly connected by a flexible conduit assembly to a tubular body having a no-go shoe formed thereon to engage the seating nipple with the jet treating head and flexible conduit assembly extending downwardly from the lower end of the tubing string. The jet treating head assembly includes a plurality of jet nozzles formed therein arranged to impart a reaction force imbalance on the head assembly in response to the application of pressurized treating fluid thereto during the jet treating of the formation. One form of the tool employs a pressure responsive fluid control valve as an integral part thereof. Treating fluid filter structure carried by the tool is also disclosed.

United States Patent [1 1 Dill [4 1 July 1,1975

[ RETRIEVABLE SELF-DECENTRALIZED HYDRA-JET TOOL Floyd E. Dill, Midland, Tex.

[73] Assignee: Halliburton Company, Duncan,

Okla.

[22] Filed: May 22, 1974 [21] Appl. No.: 472,238

[75] inventor:

[52] US. Cl. 166/222; 166/155; 166/312;

175/422 [51] Int. Cl E21b 37/00 [58] Field of Search 175/67, 231, 232, 317,

3,797,590 3/1974 Archibald et a1. .1 175/422 X Primary ExaminerDavid H. Brown Attorney, Agent, or Firm-John H. Tregoning 5 7 ABSTRACT A retrievable self-decentralized hydra-jet tool for jet treating the face of a formation penetrated by a well bore. The tool is adapted to be dropped or lowered by a wire line through a tubing string in the well bore to seat in a seating nipple at the lower end of a tubing string and to be retrieved from the tubing string by a wire line or the like after a jet treating operation. The tool includes a jet treating head assembly connected by a flexible conduit assembly to a tubular body having a no-go shoe formed thereon to engage the seating nipple with the jet treating head and flexible conduit assembly extending downwardly from the lower end of the tubing string. The jet treating head assembly includes a plurality of jet nozzles formed therein arranged to impart a reaction force imbalance on the head assembly in response to the application of pressurized treating fluid thereto during the jet treating of the formation. One form of the tool employs a pressure responsive fluid control valve as an integral part thereof. Treating fluid filter structure carried by the tool is also disclosed.

10 Claims, 9 Drawing Figures RETRIEVABLE SELF-DECENTRALIZED HYDRA-J ET TOOL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to improvements in oil and gas well stimulation, and, more particularly, but not by way of limitation, to improvements in stimulation of oil and gas wells by means of hydra-jet treatment.

2. Description of the Prior Art The employment of hydra-jet treating techniques for perforating cased holes, cutting slots or windows in casing and beyond in the formation, cutting pipe for removal, removing cement and debris from casing or open hole, under reaming, formation washing and removal of scale and debris from old perforations is well known in the oil and gas industry. A number of hydrajet tools have been developed for performance of these various processes by the oil and gas industry. in the past these tools have generally employed ajet treating head having one or more nozzles formed therein communicating between the interior and exterior of the jet treating heads. in the past it has been the usual practice to secure such jet treating heads to the lower end portion of a rigid tubing string or a rigid sub extending downwardly from a rigid tubing string which supports the jet treating head adjacent the area to be treated and provides communication between the jet treating head and the ground surface through which pressurized treating fluid is pumped. Various fluids are employed in hydrajet servicing and include abrasive laden liquids, acids and other chemical solutions adapted to the specific oil servicing job being performed.

These earlier hydra-jet tools and methods have been shown to be somewhat deficient when treating, or attempting to treat, producing formations which have been fractured by explosive and acidized thereby creating an extended stand-off distance from the axis of the well bore to the face of the formation which is to be perforated, cut, acidized or otherwise treated by means of hydra-jet equipment.

The problem of extended stand-off distance is aggravated by the relatively small diameter of the casing in many older wells coupled with the centralization of the jet treating head imparted by both the rigidity of the tubing string and the centralizer placed on the tubing string near the prior art hydra-jet treating tools thereby effectively preventing the positioning of the jet treating tool at a more effective reduced stand-off distance from the surface to be treated in cased holes, and more specifically, in shot cased holes and acidized or shot open holes.

US. Pat. application Ser. No. 448,836, filed Mar. 7, 1974, entitled Self-Decentralized Hydra-Jet Tool and assigned to Halliburton Company, the assignee of the present invention, discloses a hydra-jet tool for jet treating the face of a formation penetrated by a well bore which tool includes a jet treating head assembly adapted to be lowered into a Well bore and supported therein by a flexible conduit assembly communicating between the jet treating head assembly and a source of pressurized treating fluid. The jet treating head assembly includes a plurality of jet nozzles therein arranged such that a force imbalance is imparted to the jet treating head assembly by the reaction forces resulting from the jet active of the nozzles thereby urging the jet treating head assembly into close proximity to the formation face being treated. The jet treating head assembly disclosed in the application is mounted to the lower end of the tubing string and is run into the well bore with the tubing string. Such structure necessitates that the tubing string be withdrawn from the well bore after the jet treating operation and then rerun into the well bore if subsequent operations are to be performed on the formation being treated.

The present invention avoids this situation by allowing the tubing string to be run into the well bore first and then permitting the retrievable self-decentralized hydra-jet tool to be dropped or lowered through the tubing string to seat in a seating nipple located at the lower end thereof. After the hydra-jet treating opera tion, the hydra-jet tool of the present invention may be retrieved from the tubing string by a wire line thus permitting additional operations to be performed through the tubing string without the necessity of running a trip with the tubing string.

It has also been found suitable in prior hydra-jet treating of oil and gas wells to position some form of pressure responsive fluid control valve in the tubing string at least one joint above the prior art hydra-jet tool to provide specific control of the amount of treating fluid being employed during a treating operation. A suitable valve for this particular application is disclosed in U.S. Pat. No. 3,847,223 issued Nov. 12, l974, entitled Retrievable Fluid Control Valve and Method" and also assigned to Halliburton Company, the assignee of the present invention. This particular valve permits the predetermination of the opening pressure to which the valve will respond at the ground surface prior to dropping or lowering the valve through the tubing string to seat in a seating nipple in the tubing string one joint above the hydra-jet tool. The spring bias on the valve member of this valve is completely relaxed or deenergized prior to the introduction of the valve into the tubing string. The bias on the valve member is gradually increased as the hydrostatic head is increased above the valve in the tubing string and further increased to its predetermined opening pressure level as the fluid in the tubing string is pressurized by suitaboe suitable pumps on the ground surface. When the fluid pressure exceeds the predetermined opening pressure level the valve opens allowing pressurized fluid to pass downwardly therethrough.

One form of the present invention combines the previously described novel fluid control valve structure into a single unit with a self-decentralized hydrajet tool thus providing retrievability of the valve structure and hydra-jet treating tool structure in a single retrieving action. This advantage is extremely important in wells in which the casing is of small diameter such that the use of multiple seating nipples in a tubing string would severely reduce the size and utility of the treating tools and fluid control valve which might be employed therein. In some cases a separate fluid control valve could not be used with a retrievable treating tool because of the limited diameter of the tubing string being employed.

SUMMARY OF THE INVENTION The present invention contemplates a retrievable self-decentralized hydra-jet tool for seating in a seating nipple with a proximate to the lower end of a tubing string in a well bore for use with a source of pressurized treating fluid communicating with the tubing string for jet treating the well bore. The tool includes a tubular member having an upper end portion and a lower end portion and slidably receivable within the tubing stringv The tubular member includes annular shoulder means formed on the outer periphery thereof for engaging the seating nipple to limit downward movement thereof within the tubing string. The tool further includes a flexible conduit having an upper end portion and a lower end portion and connecting means for connecting the lower end portion of the tubular member to the upper end portion of the flexible conduit to provide communication therebetween. The tool further in cludes a jet treating head having a cavity formed therein and connecting means formed thereon for connecting the lower end portion of the flexible conduit to the jet treating head in communication with the cavity formed therein. A plurality of nozzle means are formed in the jet treating head extending outwardly from the cavity therein for ejecting pressurized treating fluid therethrough and exerting unbalanced opposite reaction forces on the jet treating head during jet treating of the well bore. The tool also includes means carried by the tubular member and extending upwardly therefrom and securable to an external source of power for unseating the tubular member from the seating nipple and retrieving the tool from the tubing string. The tool may further include filter means carried by the tubular member for filtering the pressurized treating fluid flowing therethrough from the tubing string into and through the tubular member. flexible conduit. jet treating head and plurality of nozzle means. The tool may also include fluid pressure responsive valve means carried by the tubular member for opening the tool to the flow of pressurized treating fluid through the tubular member, flexible conduit, jet treating head and plurality of nozzle means when the pressure of the treating fluid exceeds a predetermined preset pressure and, alternately, closing the tool to the flow of treating fluid therethrough when the pressure of the treating fluid is less than the predetermined present pressure.

Objects and advantages of the present invention will be evident from the following detailed description when read in conjunction with the accompanying draw mgs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. la is a partial cross-sectional view of the upper portion of the retrievable self-decentralized hydra-jet tool of the present invention positioned within a tubing string.

FIG. lb is a continuation of FIG. la and is a partial cross-sectional view of the lower portion of the retrievable self-decentralized hydra-jet tool of the present invention.

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. lb.

FIG. 3 is a diagrammatical view of the retrievable self-decentralized hydra-jet tool of the present inven tion illustrating the tool falling through the tubing string to the seating nipple.

FIG. 4 is a diagrammatical view similar to FIG. 3 il Iustrating the tool seating in the seating nipple with the valve in the closed position.

FIG. 5 is a diagrammatical view similar to FIG. 4 illustrating the tool seated in the seating hippie with the 4 valve in the open position during a jet treating operation.

FIG. 6 is a diagrammatical view similar to FIG. 5 illustrating the tool unseated from the seating nipple during retrieval from the tubing string.

FIG. 7 is a partial cross-sectional view of another form of retrievable self-decentralized hydra-jet tool of the present invention positioned within a tubing string.

FIGv 8 is a crosssectional view taken along line 8-8 of FIG. 7.

DETAILED DESCRIPTION Referring now to the drawings, and to FIGS. la and lb in particular, the retrievable self-decentralized hydra-jet tool of the present invention is generally designated by the reference character 10. The tool 10 comprises a valve body 12, a valve member 14 carried by the valve body, a piston 16 carried by the valve body, and a compression spring 18 carried by the valve body and positioned intermediate the valve member l4 and the piston 16.

The valve body 12 is in the form of an elongated, generally tubular member having a lower or first end portion 20 and an upper or second end portion 22. A longitudinal passageway 24 extends through the valve body 12 and intersects the first and second end portions 20 and 22 thereof. The outer periphery 26 of the valve body 12 is substantially cylindrical in shape. The valve body 12 includes a lower guide member 28 which is threadedly secured at the upper end 30 thereof within a no-go shoe or ring 32. An annular seal 34 provides a fluid-tight connection between the guide member 28 and the no-go shoe 32. An annular seal 36 is positioned in a circumferential groove 38 formed in the guide member 28 and is securely retained therein by the guide member 28 and the no-go shoe 32. The outer periphery 40 of the annular seal 36 is suitably sized to provide a fluid-tight seal between the tool 10 and a seating nipple 42 of the tubing string 44. The seal 36 may be suitably formed of an elastomeric or synthetic resilient material.

The guide member 28 includes a longitudinal passageway 46 formed therein with a cylindrically shaped upper portion 30 communicating with a cylindrically shaped inner periphery 48 of the nogo shoe 32 having an internally threaded lower portion. The longitudinal passageway 46 and the inner periphery 48 form a portion of the passageway 24 through the valve body 12. The diameter of the outer periphery 50 of the no-go shoe 32 is suitably sized such that it is less than the inner diameter of the tubing string 44 and is greater than the diameter of the inner periphery 52 of the seating nipple 42 thereby providing a positive support for the tooi 10 within the tubing string 44.

The upper end portion 54 of the no-go shoe 32 is threadedly secured within the lower end portion 56 of the flow port member 58. An annular seal 60 provides a fluid-tight seal between the no-go shoe 32 and the flow port member 58. The flow port member 58 includes a first cylindrically shaped inner surface 62 coaxially aligned with the longitudinal axis of the tool 10 and the longitudinal passageway 46 and inner periphery 48 of the member 28 and the no-go shoe 32. The diameter of the inner surface 62 is greater than the diameter of the inner periphery 48 of the no-go shoe 32. An annular wall 64 is formed on the upper end portion 54 of the no-go shoe 32 and extends between the inner periphery 48 of the no-go shoe and the first cylindrically shaped inner surface 62. A plurality of circumferentially spaced, radially extending flow control ports 66 are formed in the flow port member 58 and communicate between the inner surface 62 and the cylindrically shaped outer periphery 68 thereof.

The upper end portion 70 of the flow port member 58 is threadedly secured within the lower end portion 72 of the actuator port member 74. The actuator port member 74 includes a medial cylindrically shaped inner surface 76 coaxially aligned with the surface 62 and extending upwardly from a point near the threaded interconnection between the actuator port member 74 and the flow port member 58.

A second cylindrically shaped inner surface 78, having a diameter less than the diameter of the medial cylindrically shaped inner surface 76 and coaxially aligned therewith, extends downwardly from the upper end portion 80 of the actuator port member 74. An annular wall 82 is formed on the actuator port member 74 and interconnects the cylindrically shaped inner surfaces 76 and 78. An upper end face 84 is formed on the upper end portion 80 of the actuator port member 74.

At least one actuator port 86 extends radially through the actuator port member 74 and communicates between an annular chamber 88, having a diameter slightly greater than the diameter of the medial cylindrically shaped inner surface 76 and positioned intermediate the medial cylindrically shaped inner surface 76, and the upper end portion 70 of the flow port member 58. Each actuator port 86 communicates between the annular chamber 88 and the cylindrically shaped outer periphery 90 of the actuator port member 74.

The upper end portion 80 of the actuator port member 74 is threadedly secured within the lower end portion 92 of a cylindrically shaped spring housing 94. An annular seal 95 provided a fluid-tight seal between the actuator port member 74 and the spring housing 94. The upper end portion 96 of the spring housing 94 is threadedly secured about the lower end portion 98 of a piston-retaining collar 100. An annular seal 102 provides a fluid-tight seal between the spring housing 94 and the piston-retaining collar 100.

The collar 100 includes a cylindrically shaped inner surface 104 extending therethrough in substantial coaxial alignment with the longitudinal axis of the tool 10. A pair of annular grooves 106 are formed in the collar 100 and extend radially outwardly from the inner surface 104. A suitable annular seal member 108, such as an O-ring, is disposed within each groove 106 for purposes which will be described more fully hereinafter.

The piston-retaining collar 100 also includes a lower end face 110 and an upper end face 112.

The piston 16, having a cylindrically shaped outer periphery 116 formed thereon, is slidably disposed within the cylindrically shaped inner surface 104 of the pistonretaining collar 100. The piston 16 is adapted for longitudinal movement relative to the collar 100. The seals 108 provide a fluid-tight sliding seal between the piston 16 and the piston-retaining collar 100.

An outwardly extending flange 118 is formed on the lower end portion 120 of the piston 16. Upward movement of the piston 16 relative to the collar 100 is restricted by the abutment of the flange 118 with the lower end face 110 of the collar 100. The upper end portion 122 or rod end of the piston 16 extends outwardly through the collar and is threadedly secured within the lower end portion 124 of a fishing neck 126. The fishing neck 126 includes a lower end face 128 which limits the downward movement of the piston 16 relative to the collar 100 by abutting the upper end face 112 of the piston-retaining collar 100. The upper end portion 130 of the fishing neck 126 includes a transverse aperture 132 formed therein which may be secured to a wire line or the like for lowering the tool 10 downwardly through the tubing string 44 and, alternately, retrieving the tool 10 upwardly through the tubing string 44. A lower end face 134 is formed on the lower end portion 120 of the piston 16.

The valve member 14 comprises a lower element 136 and an upper element 138. The upper end portion 140 of the lower element 136 is threadedly secured within the lower end portion 142 of the upper element 138. An annular seal 144 provides a fluid-tight seal between the lower element 136 and the upper element 138.

The lower or first end portion 146 of the valve member 14 includes a cylindrically shaped outer periphery 148 sized to provide a sliding fit within the first cylindrically shaped inner surface 62 of the valve body 12. A pair of annular grooves 150 are formed in the cylindrically shaped outer periphery 148 and extend radially inwardly therefrom. A pair of annular seal members 152, such as O-rings, are disposed respectively in the grooves 150 and provide a sliding, fluid-tight seal between the lower end portion 146 of the valve member 14 and the first cylindrically shaped inner surface 62 of the valve body 12.

A cylindrically shaped outer periphery 154 is formed on the medial portion 156 of the valve member 14. The cylindrically shaped outer periphery 154 is sized and shaped to be slidably received within the medial cylindrically shaped inner surface '76 of the valve body 12. A pair of annular grooves 158 are formed in the cylindrically shaped outer periphery 154 and extend radially inwardly therefrom. A pair of annular seal members 160, such as O-rings, are disposed respectively in the annular grooves 158 and provide a sliding, fluid-tight seal between the medial portion 156 of the valve member 14 and the medial cylindrically shaped inner surface 76 of the valve body 12.

A cylindrically shaped outer periphery 162 is formed on the upper or second end portion 164 of the valve member 14. The cylindrically shaped outer periphery 162 is sized and shaped to provide a close, sliding fit within the second cylindrically shaped inner surface 78 of the valve body 12. A pair of annular grooves 166 are formed in the cylindrically shaped outer periphery 162 and extend radially inwardly therefrom. A pair of annular seal members 168, such as O-rings, are disposed respectively within the annular grooves 166 and provide a sliding, fluid-tight seal between the upper or second end portion 164 of the valve member 14 and the second cylindrically shaped inner surface 78 of the valve body 12.

An annular recess 170 is formed in the outer periphery of the valve member 14 intermediate the cylindrically shaped outer periphery 148 and the cylindrically shaped outer periphery 154. Annular recesses 172 and 174 are formed on the outer periphery of the valve member 14 intermediate the cylindrically shaped outer periphery 154 and the cylindrically shaped outer periphery 162. The annular recesses 172 and 174 are connected by a radial wall 175.

A cylindrically shaped, blind cavity 176 is formed in the valve member 14 and intersects the lower end face 178 of the valve member 14. A pressure equalization port 180 is formed in the valve member 14 and communicates between the cavity 176 and the annular recess 172.

The upper end face 182 of the valve member 14 abuts the lower end face 184 of a spring stop 186. The spring stop 186 has a cylindrically shaped outer periphery 188 having a diameter greater than the diameter of the second cylindrically shaped inner surface 78 of the valve body 12.

The compression coil spring 18 is disposed within the spring housing 94 and intermediate the piston 16 and the spring stop 186. The upper end 190 of the spring 18 abuts the lower end face 134 of the piston 16, while the lower end 192 of the spring 18 abuts the upper end face 194 of the spring stop 186.

The retrievable self-decentralized hydra-jet tool further includes a volume tube assembly 200 connected to the valve body 12, and a flexible conduit assembly 202 interconnecting the volume tube assembly 200 and a jet treating head assembly 204.

The jet treating head assembly 204 includes a head member 206 having a cavity 208 formed therein. A treating nozzle passageway 210 is formed in the head member 206 and communicates between the cavity 208 and the outer periphery 212 of the head member 206. Two reaction nozzle passageways 214 and 216 also communicate between the cavity 208 and the outer periphery 212 of the head member 206 and extend from the cavity 208 in a direction substantially opposite to the direction the treating nozzle passageway 110 extends from the cavity 208.

Each of the nozzle passageways 210, 214 and 216 preferably includes a relatively hard, abrasive-resistant nozzle insert 218 suitably secured therein, such as by mutually threaded engagement, with a passageway or bore 220 formed in each insert 218 providing communication between the respective nozzle passageway and the exterior of the head member 206. FIG. 2 illustrates a suitable arrangement of nozzle inserts 218 in the head member 206 of the jet treating head assembly 204.

The flexible conduit assembly 202 comprises an elongated flexible tubular conduit member 222 having an upper end portion 224 and a lower end portion 226. The flexible tubular conduit member 222 is preferably formed of high-pressure, reinforced rubber hose. Hose suitable for this application is manufactured by Stratoflex, Inc. and is designated as SF 238 hose.

A high-pressure hose fitting 228 is connected to the lower end portion 226 of the flexible tubular member 222 and is in turn threadedly secured to the upper end portion 230 of the head member 206 placing the flexible conduit assembly 202 in communication with the cavity 208 of the jet treating head assembly 204. Another high-pressure hose fitting 232 is connected to the upper end portion 224 of the flexible tubular conduit member 222.

The length of the flexible conduit assembly 202 may be varied for various jet treating applications depe ing on the characteristics of the formation to t treated, however, a length of approximately ten fee is considered to provide satisfactory results.

The volume tube assembly 200 comprises an elm gated tubular member 234 having an upper end portion 236 and a lower end portion 238. A longitudinal passageway 240 extends through the tubular member 234 intersecting the upper and lower end portions 236 and 238. A tubular adapter 242 is threadedly secured within the lower end portion 238 of the elongated tubular member 234. The tubular adaptor 242 includes a longitudinal passageway 244 extending therethrough. The high-pressure hose fitting 232 is threadedly secured within the lower portion of the longitudinal passageway 244. The upper end portion 236 is threadedly secured to the internally threaded lower portion of the longitudinal passageway 46 of the lower guide member 28. The longitudinal passageway 240 and the longitudinal passageway 244 provide communication between the longitudinal passageway 46 of the guide member 28 of the valve body 12 and the flexible conduit assembly 202.

An elongated tubular strainer or filter 246 is threadedly secured at the lower end portion 248 thereof within an internally threaded portion of the longitudinal passageway 244 of the tubular adaptor 242. The strainer or filter 246 is closed at its upper end 250 and includes a plurality of perforations 252 formed therein providing communication between the interior and the exterior of the strainer 246. The interior of the strainer 246 is in communication with the longitudinal passageway 244 of the tubular adaptor 242. The perforations 252 are preferably formed each with a diameter less than the diameter of the passageways 220 in the nozzle inserts 218 to prevent foreign matter from inadvertently plugging the passageways during the operation of the tool 10.

Operation of the Embodiment of FIGS 10, lb and 2 The operation of the retrievable self-decentralized hydra-jet tool 10 is diagrammatically illustrated in FIGS. 3, 4, 5 and 6. FIG. 3 diagrammatically illustrates the relationship of the various elements of the tool 10 as the tool 10 is being dropped through the tubing string 44 to its ultimate seating position on the seating nipple 42. The tool 10 may be allowed to freely fall through the tubing string 44, as shown in FIG. 3, or it may be lowered by means ofa wire line (not shown) secured through the aperture 132 in the fishing neck 126. In either case, the relationship of the elements of the tool 10 will be as diagrammatically illustrated in FIG. 3.

It will be understood in FIG. 3 that, as the tool 10 is moving downwardly through the tubing string 44, the valve member 14 is at its lowest position within the valve body 12. In this case, the lower end face 178 of the valve member 14 abuts the annular end wall 64 of the valve body 12. The annular seal members 152 sealingly engage the first cylindrically shaped inner surface 62 of the valve body 12 below the flow control port 66. When the valve member 14 is in this position relative to the valve body 12, the tool 10 is in the closed posi tion.

FIG. 4 diagrammatically illustrates the retrievable self-decentralized hydra-jet tool 10 in its seated position with the no-go shoe 32 engaging the seating nipple 42. It will also be understood that the tubing string 44, illustrated in FIG. 4, has been loaded with suitable treating fluid which is confined within the tubing strirg 44 by means of the closed valve structure in the tool 10.

The piston 16 is forced downwardly in response to the hydrostatic pressure of the fluid in the tubing string 44 acting across the area defined by the diameter of the outer periphery 116 of the piston 16. The downward movement of the piston 16 is resisted only by the compression spring 18 and the air at atmospheric pressure trapped within the longitudinal passageway 24 of the valve body 12 between the annular sea] members 108 and 168.

When the piston 16 is moved completely downwardly by the fluid pressure within the tubing string, the compression spring 18 is compressed to its predetermined valve-opening value. the valve-opening value is determined at the time of assembly of the tool at the ground surface by the spring rate of the compression spring 18 and the length of stroke of the piston 16 employed in the tool 10. For a compression spring 18 of a given spring rate, various valve-opening values may be predetermined by selecting a piston-retaining collar 100 having a specific longitudinal length from the lower end face 110 to the upper end face 112. It will be understood that the greater the longitudinal distance between the lower end face 110 and the upper end face 112, the less the spring 18 can be compressed by the piston 16 and, therefore, the lower the predetermined valve-opening pressure. It will also be apparent that by selecting a shorter piston-retaining collar 100, a higher valve-opening pressure will be obtained. By proper selection of the spring 18 and piston-retaining collar I00, the tool 10 may be preset so that the piston 16 will be forced to its lowermost position compressing the spring 18 when the tubing string 44 is filled with treating fluid above the tool 10. It should be understood that the spring 18 is fully relaxed or de-energized when the tool 10 is fully assembled at the ground surface prior to its introduction down into the tubing string 44.

As the hydraulic pressure within the tubing string 44 is increased by the pumping action, the fluid communicating with the cross-sectional area of the valve member 14 defined by the diameter of the medial cylindrically shaped inner surface 76 and the first cylindrically shaped inner surface 62 through the actuator port 86 overcomes the downward bias of the spring 18 on the valve member 14 and forces the valve member 14 upwardly into the open position. When the valve member 14 has moved upwardly into the open position, the radial wall 175 of the valve member 14 abuts the annular wall 82 of the valve body 12 thus limiting the upward movement of the valve member 14 relative to the valve body 12. Under these conditions it will be seen that the annular seal members 152 will be positioned above the flow control ports 66, thereby allowing fluid to flow through the flow control ports 66 into the passageway 24 through the valve body 12 and downwardly into the longitudinal passageway 240 of the tubular member 234, through the perforations 252 into the interior of the strainer or filter 246, through the longitudinal passageway 244 of the tubular adaptor 242, through the flexible conduit assembly 202 and into the jet treating head assembly 204 where the fluid is ejected therefrom through the bores 220 of the nozzle inserts 218. This latter condition is diagrammatically illustrated in FIG. 5.

Because the differential area defined by the diameters of the medial and first cylindrically shaped inner surfaces 76 and 62 is specifically designed to be slightly less than the area defined by the diameter of the outer periphery [[6 of the piston 16, the upward movement of the valve member 14 can only compress the compression spring 18, and the piston 16 will remain in its lowermost position.

It should also be noted that when the valve structure of the tool 10 is in the open position. fluid pressure acting through the cavity 176 and the pressure equalization port 180 is applied to a differential cross-sectional area defined by the diameters of the medial and second cylindrically shaped inner surfaces 76 and 78, which differential area is equal to the cross-sectional area defined by the diameter of the first cylindrically shaped inner surface 62. This differential area relationship prevents the pressure below the valve structure of the tool 10 from having any effect on the operation of the valve member 14 within the valve body 12.

Referring again to FIG. 5, as the pump (not shown) continues to provide pressurized treating fluid downwardly through the tubing string 44 and through the hydra-jet tool 10, a force differential is applied to the jet treating head assembly 204 by means of the reaction forces resulting from the jet flow of treating fluid through the treating nozzle passageway 210 and the reaction nozzle passageways 2l4 and 216 and their respective nozzle inserts 218. The passageways or bores 220 of the nozzle inserts 218 are preferably of substantially identical diameter and cross-sectional area. thereby providing a reaction force differential acting on the jet treating head assembly 204 which urges the jet treating head assembly 204 in the direction of the jet ejecting from the treating nozzle passageway 210, or to the left as viewed in FIGS. 2 and 5. In FIG. 5 it will be seen that the jet treating head assembly 204 is decentralized transversely to the left relative to the axis of the well bore into close proximity or contact with the face of the formation to be hydra-jet treated. This transverse decentralization of the jet treating head assembly 204 is permitted by the employment of the flexible conduit assembly 202 which provide flexible support for the jet treating head assembly 204 from the tubing string 44 via the volume tube assembly 200 and the valve body 12 of the hydra-jet tool 10 thereby allowing the jet treating head assembly 204 to swing freely within the well bore in response to the reaction force of the jets acting thereon.

It will be understood that other configurations, quantities and diameters of treating and reaction nozzles may be employed in a jet treating head assembly as long as they provide the necessary reaction force imbalance on a jet treating head assembly to decentralize it transversely into close proximity or contact with the formation face being treated.

As the hydra-jet treating of the formation continues, the tubing string 44 and the retrievable selfdecentralized hydra-jet tool may be rotated about the axis of the well bore by manually rotating the tubing string 44 from the ground surface by suitable means such as a hand wheel or the like (not shown) engageable with the upper end portion of the tubing string 44. The vertical position of the jet treating head assembly 204 relative to the formation being treated may be readily adjusted by raising or lowering the tubing string 44 by means of a cable (not shown) or the like connected to the upper end of the tubing string and supported by a conventional derrick structure during the jet treating operation or between various stages of the jet treating operation to provide selective interval treatment.

Various pressurized treating fluids may be employed with the retrievable self-decentralized hydra-jet tool depending on the nature of the formation being treated and the type of well stimulation required.

In those cases where it is known that the zone to be hydra-jet treated is a definite distance above the bottom of the well bore, the tubing string 44, without the retrievable self-decentralized hydra-jet tool 10 posi tioned therein, may be lowered within the well bore until the lower end of the tubing string 44 contacts the bottom of the well bore and then the tubing string 44 may be raised an amount equal to the height of the zone to be treated above the bottom of the well bore plus the length of the flexible conduit assembly 202 which will ultimately extend below the bottom end of the tubing string 44 to properly position the tubing string vertically within the well bore. The retrievable self-decentralized hydra-jet tool 10 may then be lowered or dropped downwardly through the tubing string 44 and operated in the manner as described above.

When the pumping ceases, and the pressure on the fluid in the tubing string 44 is allowed to fall below the predetermined opening pressure of the valve structure of the tool 10, the spring 18 forces the valve member 14 downwardly thereby closing the flow control port 66, thus placing the valve structure above the tool back in the condition diagrammatically illustrated in FIG. 4.

When treatment has been completed and pumping has been discontinued, a conventional overshot 254 may be lowered through the tubing string 44 on a line or cable 256 connected to suitable hoisting means at the ground surface (not shown) to engage the upper end portion 130 of the fishing neck 126 and may be pulled upwardly after engagement to move the piston 16 upwardly thereby releasing any compression forces on the spring 18 placing it in a relaxed completely deenergized condition. This action may also be accomplished by moving the fishing neck 126 upwardly by pulling a wire line (not shown) engaged through the aperture 132 upwardly through the tubing string 44. This action allows the hydraulic pressure within the tubing string 44 to operate through the actuator port 86 on the differential area defined by the diameters of the first cylindrically shaped inner surface 62 and the medial cylindrically shaped inner surface 76 to move the valve member 14 up into the open position. This movement of the valve member 14 allows the tubing pressure to equalize through the tool 10 through the flow control port 66, cavity 176, volume tube assembly 200, flexible conduit assembly 202 and jet treating head assembly 204 into the tubing string 44 below the tool 10 to perform a by-passing action so that the tool 10 can be retrieved off its seat on the seating nipple 42. FIG. 6 diagrammatically shows the relationship of the elements of the retrievable self-decentralized hydra-jet tool 10 during the retrieval of the tool 10 from the tubing string 44.

It should be clearly understood that the valve structure of the retrievable self-decentralized hydra-jet tool 10 is neither capable of nor intended for checking upward flow of fluid from the well bore into the tubing string 44 since the tool 10 merely rests on the seating nipple 42 and is never attached to the tubing string.

Description of the Embodiment of FIGS. 7 and 8 FIG, 7 illustrates another form of retrievable selfdecentralized hydra-jet tool which is generally designated by the reference character 310. The tool 310 comprises a jet treating head assembly 312, a tubular support assembly 314, and a flexible conduit assembly 316 interconnecting the jet treating head assembly 312 and the tubular support assembly 314.

The jet treating head assembly 312 includes a head member 318 having a cavity 320 formed therein. As shown in H0. 8, a treating nozzle passageway 322 is formed in the head member 318 and communicates between the cavity 320 and the outer periphery 324 of the head member 318. Two reaction nozzle passageways 326 and 328 also communicate between the cavity 320 and the outer periphery 324 of the head member 318 and extend from the cavity 320 in directions substantially opposite to the direction the treating nozzle passageway 322 extends from the cavity 320. Each of the nozzle passageways 322, 326 and 328 preferably includes a relatively hard, abrasive-resistant nozzle insert 330 suitably secured therein such as by mutually threaded engagement, with a passageway or bore 332 formed in each insert 330 providing communication between the respective nozzle passageway and the exterior of the head member 318.

The flexible conduit assembly 316 comprises an elongated flexible tubular conduit member 334 having an upper end portion 336 and a lower end portion 338. The flexible tubular conduit member 334 is preferably formed of high-pressure, reinforced rubber hose.

A high-pressure hose fitting 340 is connected to the lower end portion 338 of the flexible tubular member 334 and is in turn threadedly secured to the head member 318 of the jet treating head assembly 312 placing the flexible conduit assembly 316 in communication with the cavity 320 of the jet treating head assembly 312. Another high-pressure hose fitting 342 is connected to the upper end portion 336 of the flexible tubular conduit member 334.

The length of the flexible conduit assembly 316 may be varied for various jet treating applications depend ing on the characteristics of the formation to be treated and the diameter of the well bore penetrated thereby, however, a length of approximately ten feet is considered to provide satisfactory results in the employment of the tool 310.

The tubular support assembly 314 comprises a lower tubular member 344 having an upper end portion 346, a lower end portion 348 and a longitudinal passageway 3S0 extending therethrough and communicating between the upper and lower end portions 346 and 348. The lower tubular member 344 includes a substantially cylindrical outer periphery 352 having a plurality of annular grooves 354 formed therein intermediate the upper and lower end portions 346 and 348 in which annular resilient seal members 356 are carried. The lower end portion 348 of the lower tubular member 344 is threadedly secured to the hose fitting 342 of the flexible conduit assembly 316 to provide communication between the passageway 350 and the flexible conduit assembly 316.

The tubular support assembly 314 further includes :1 h0g0 shoe 358 having an upper end portion 360 and a lower end portion 362 with a longitudinal passageway 364 extending therethrough and communicating between the upper and lower end portions 360 and 362. The lower end portion 362 is threadedly secured to the upper end portion 346 of the lower tubular member 344 thereby placing the longitudinal passageways 364 and 350 in communication. An outwardly extending annular shoulder 366 is formed on the lower end portion 362 of the no-go shoe 358 providing means for engagement with the seating nipple 42 of the tubing string 44 as will be described more fully hereinafter.

The tubular support assembly 314 further includes a tubular strainer or filter 368 threadedly secured at the lower end portion 370 thereof to the upper end portion 360 of the no-go shoe 358. A cage 372 is threadedly secured to the lower end portion 370 of the strainer 368 and provides additional structural support therefor.

A conventional fishing neck 374 is threadedly secured in the upper end portion 376 of the strainer 368 thereby closing the upper end of the tubular strainer. A plurality of perforations 378 are formed inn the strainer 368 providing communication between the interior and the exterior of the strainer 368. The interior of the strainer 368 is in communication with the passageway 364 of the no-go shoe 358. The perforations 378 are preferably formed each with a diameter less than the diameter of the bores or passageways 332 in the nozzle inserts 330 to prevent foreign matter from inadvertently plugging the passageways during the operation of the retrievable self-decentralized hydra-jet tool 310. The fishing neck 374 includes a transverse aperture 380 formed therein through which a wire line may be connected to lower and retrieve the tool 310 within the tubing string 44 if desired. An annular rib 382 may also be formed on the fishing neck 374 to facilitate the engagement of the fishing neck 374 by a conventional overshot for retrieval of the tool 310 from the tubing string 44.

Operation of the Embodiment of FIGS. 7 and 8 To operate the retrievable self-decentralized hydrajet tool 310, it will be understood that the tubing string 44 with the seating nipple 42 secured to the lower end thereof must first be positioned within the well bore which is to be jet treated. When the tubing string 44 is vertically positioned within the well bore for the jet treating of a formation penetrated thereby, the tool 310 is either dropped through the tubing string 44 of lowered by means ofa wire line (not shown) secured to the aperture 380 of the fishing neck 374 until the jet treating head assembly 312 and the flexible conduit assembly 316 extend downwardly through the seating nipple 42 and the annular shoulder 366 of the no-go shoe 358 is seated on the seating nipple 42, as shown in FIG. 7. The annular seal members 356 provide a fluid-tight seal between the tubular support assembly 314 and the inner periphery of the seating nipple 42.

Suitable jet treating fluid is then pumped down through the tubing string 44 and through the hydra-jet tool 310. A force differential is then applied to the jet treating head assembly 312 by means of the reaction forces resulting from the jet flow of treating fluid through the treating nozzle passageway 322 and the reaction nozzle passageways 326 and 328 and their respective nozzle inserts 330. The action of the jet treating head assembly 312 in response to the application of these unbalanced reaction forces is identical to that described above for the tool 10 and need not be repeated again. Also, as mentioned for the tool 10, rotation of the jet treating head assembly 312 may be readily achieved by rotating the tubing string 44 from the ground surface.

When the treatment has been completed and pumping has been discontinued, a conventional overshot (not shown) may be lowered through the tubing string 44 to engage the annular rib 382 of the fishing neck 374 and may be pulled upwardly by means of a suitable line or cable to retrieve the tool 310 from its position in the seating nipple 42 upwardly through the tubing string.

It will be readily apparent that the employment of various embodiments of the present invention will permit a user to perform various tests and well logging operations, both before and after use of the present invention for jet treating a well bore, through the same tubing string without the necessity of removing the tubing string from the well bore for installation and removal of the jet treating apparatus.

Changes may be made in the construction and arrangement of parts or elements of the various embodiments disclosed above without departing from the spirit and scope of the invention as defined herein.

What is claimed is:

1. A retrievable self-decentralized hydra-jet tool for seating in a seating nipple within and proximate to the lower end of a tubing string in a well bore for use with a source of pressurized treating fluid communicating with the tubing string for jet treating the well bore, comprising:

a. a tubular member, having an upper end portion and a lower end portion and slidably receivable within the tubing string, said tubular member having annular shoulder means formed on the outer periphery thereof for engaging the seating nipple to limit downward movement thereof within the tubing string;

b. a flexible conduit having an upper end portion and a lower end portion;

c. connecting means for connecting the lower end portion of said tubular member to the upper end portion of said flexible conduit to provide communication therebetween;

d. a jet treating head having a cavity formed therein and connecting means formed thereon for connecting the lower end portion of said flexible conduit to said jet treating head in communication with the cavity formed therein;

e. first nozzle means, formed in said jet treating head and extending outwardly from the cavity therein in a first direction, for ejecting pressurized treating fluid therethrough in the first direction and exerting a first reaction force on said jet treating head in a direction substantially opposite said first direc tion;

f. second nozzle means, formed in said jet treating head and extending outwardly from the cavity in a second direction substantially opposite said first direction of said first nozzle means, for ejecting pressurized treating head in the second direction and exerting a second reaction force on said jet treating head in a direction substantially opposite said second direction, said second reaction force being greater than said first reaction force; and

g. means, carried by said tubular member and extending upwardly therefrom, for engaging an external retrieving device, for unseating said tubular member from the seating nipple in response to operation of said retrieving device and for retrieving said tool from the tubing string in response to further operation of said retrieving device.

2. The retrievable self-decentralized hydra-jet tool as defined in claim 1 characterized further to include:

filter means carried by said tubular member for filtering the pressurized treating fluid flowing therethrough from the tubing string into and through said tubular member, flexible conduit, jet treating head and plurality of nozzle means.

3. The retrievable self-decentralized hydra-jet tool as defined in claim 1 characterized further to include:

fluid pressure responsive valve means carried by said tubular member for opening said tool to the flow of pressurized treating fluid through said tubular member, flexible conduit, jet treating head and plu rality of nozzle means when the pressure of the treating fluid exceeds a predetermined preset opening pressure and, alternately, closing said tool to said flow of treating fluid therethrough when the pressure of the treating fluid is less than the predetermined preset opening pressure.

4. A retrievable self-decentralized hydra-jet tool for seating in a seating nipple within and proximate to the lower end of a tubing string in a well bore for use with a source of pressurized treating fluid communicating with the tubing string to control the flow of treating fluid downwardly through the tubing string in response to fluid pressure applied thereto and jet treat the well bore, comprising:

a valve body having opposite end portions and a longitudinal passageway extending therethrough and having a fluid flow control port and a valve member actuator port formed therein, each port communicating between the passageway and the outer periphery of said valve body;

a valve member slidably disposed within the passageway of said valve body for longitudinal movement therein between a closed position blocking fluid flow between the outer periphery of said valve body and the passageway therethrough and an open position allowing fluid flow between the outer periphery of said valve body and the passageway through the fluid flow control port responsive to fluid pressure acting thereon through the valve member actuator port in said valve body;

means formed on said valve body intermediate one end portion thereof and the fluid flow control port for seating the valve body in the seating nipple;

means formed on said valve body for providing a fluid-tight seal between the outer periphery of said valve body and the tubing string intermediate the fluid flow control port and the one end portion thereof;

piston means slidably disposed in the passageway adjacent to the opposite end portion of said valve body and longitudinally movable therein in response to the fluid pressure within the tubing string acting thereon;

biasing means disposed intermediate said valve member and said piston means for urging said valve member into the closed position in response to the movement of said piston means responsive to the application of fluid pressure to said piston means;

a tubular member, having an upper end portion and a lower end portion, connected at its upper end portion to the one end portion of said valve body in communication with the longitudinal passageway therethrough;

a flexible conduit, having an upper end portion and a lower end portion, connected at its upper end 5 portion to the lower end portion of said tubular member in communication therewith;

a jet treating head having a cavity formed therein and connecting means formed thereon for connecting the lower end portion of said flexible conduit to said jet treating head in communication with the cavity formed therein; and

a plurality of nozzle means formed in said jet treating head and extending outwardly from the cavity therein for ejecting pressurized treating fluid therethrough and exerting unbalanced opposite reaction forces on said jet treating head during jet treating of the well bore.

5. The retrievable self-decentralized hydra-jet tool as defined in claim 4 characterized further to include: filter means disposed within said tubular member intermediate said valve body and said flexible conduit for filtering the pressurized treating fluid flowing therethrough from the valve body and through said tubular member, flexible conduit, jet treating head and nozzle means.

6. The retrievable self-decentralized hydra-jet tool as defined in claim 4 characterized further to include:

means carried by said valve body and engageable with said piston means for limiting the movement of said piston means in response to fluid pressure acting thereon whereby said biasing means urges said valve member into the closed position with a force corresponding to a predetermined valveopening fluid pressure. 7. The retrievable self-decentralized hydra-jet tool as defined in claim 6 characterized further to include:

means securable to said piston means and responsive to an external force applied thereto for moving said piston means in a direction opposite to the direction of movement thereof responsive to fluid pressure within the tubing string, 8. The retrievable self-decentralized hydra-jet tool as defined in claim 6 characterized further to include:

means securable to said piston means and responsive to an external force for moving said piston means in a direction opposite to the direction of movement thereof responsive to fluid pressure within the tubing string, and unseating said valve body from said seating nipple and retrieving said tool from said tubing string.

9. A pressure actuated self-decentralized hydra-jet tool for controlling the flow of treating fluid through a conduit in response to fluid pressure within the conduit and for jet treating a well bore in which the conduit is positioned, comprising:

a valve body positionable within the conduit, said valve body having an outer periphery, a first end portion and a second end portion, and having a longitudinal passageway extending therethrough and intersecting the first and second end portions;

conduit seal means carried by said valve body for sealingly engaging the inner periphery of the conduit proximate the lower end thereof;

piston means slidably disposed in the passageway through said valve body adjacent to the second end portion thereof for longitudinal movement within said valve body;

retaining means formed on the second end portion of said valve body for retaining said piston means within said valve body;

rod means connected to said piston means and having the outer end thereof extending through said retaining means for communicating with the fluid in the conduit;

limit means secured to the outer end of said rod means for limiting the longitudinal movement of said piston means within said valve body toward the first end portion thereof;

means carried by said rod means securable to an external source of power for moving said piston means longitudinally within said valve body toward the second end portion thereof;

a valve member slidably disposed within the passageway through said valve body intermediate the first end portion thereof and said piston means, said valve member having an outer periphery, a first end portion positioned proximate to the first end portion of said valve body, a second end portion positioned proximate to said piston means, and a medial portion intermediate said first and second end portions, said valve member having a cavity formed therein and intersecting the first end portion thereof and having a port formed therein communicating between the cavity and the outer periphery of said valve member intermediate the medial portion and the second end portion thereof;

a first cylindrically shaped inner surface formed in the passageway of said valve body adjacent to the first end portion of said valve member;

a second cylindrically shaped inner surface formed in the passageway of said valve body adjacent to the second end portion of said valve member;

a medial cylindrically shaped inner surface formed in the passageway of said valve body intermediate the first and second cylindrically shaped inner surfaces and adjacent to the medial portion of said valve member, said medial cylindrically shaped inner surface having a diameter greater than the diameter of the first cylindrically shaped inner surface and greater than the diameter of the second cylindrically shaped inner surface;

first seal means carried by the first end portion of said valve member for providing a sliding seal between the first end portion of said valve member and the first cylindrically shaped inner surface of said valve body;

second seal means carried by the second end portion of said valve member for providing a sliding seal between the second end portion of said valve member and the second cylindrically shaped inner surface of said valve body;

medial seal means carried by the medial portion of said valve member for providing a sliding seal between the medial portion of said valve member and the medial cylindrically shaped inner surface of said valve body;

means carried by said valve body for restricting the sliding movement of said valve member within the passageway of said valve body between a closed position proximate to the first end portion of said valve body and an open position distal from the first end portion of said valve body;

biasing means disposed within the passageway through said valve body intermediate the second end portion of said valve member and said piston means for urging said valve member longitudinally away from said piston means into the closed position;

fluid flow control port formed in said valve body and communicating between the outer periphery thereof and the passageway therethrough, said fluid flow control port being positioned in said valve body such that when said valve member is in the closed position said first seal means is positioned longitudinally intermediate said fluid flow control port and the first end portion of said valve body, and when said valve member is in the open position said first seal means is positioned longitudinally intermediate said fluid flow control port and the second end portion of said valve body; valve member actuating port formed in said valve body and communicating between the outer periphery thereof and the passageway therethrough, said valve member actuating port being positioned in said valve body such that it remains longitudinally intermediate said first seal means and said medial seal means in all longitudinal positions of said valve member relative to said valve body;

a tubular member, having an upper end portion and a lower end portion, connected at the upper end portion thereof to the first end portion of said valve body in communication with the longitudinal passageway therethrough;

flexible conduit, having an upper end portion and a lower end portion, connected at the upper end portion thereof to the lower end portion of said tubular member in communication therewith;

jet treating head, having a cavity formed therein and connecting means carried thereby for connecting the lower end portion of said flexible conduit to said jet treating head in communication with the cavity; and

a plurality of nozzle means formed in said jet treating head and extending outwardly from the cavity therein for ejecting pressurized treating fluid there through and exerting unbalanced opposite reaction forces on said jet treating head during jet treating of the well bore.

10. The retrievable self-decentralized hydra-jet tool as defined in claim 9 characterized further to include:

filter means disposed within said tubular member inand nozzle means. 

1. A retrievable self-decentralized hydra-jet tool for seating in a seating nipple within and proximate to the lower end of a tubing string in a well bore for use with a source of pressurized treating fluid communicating with the tubing string for jet treating the well bore, comprising: a. a tubular member, having an upper end portion and a lower end portion and slidably receivable within the tubing string, said tubular member having annular shoulder means formed on the outer periphery thereof for engaging the seating nipple to limit downward movement thereof within the tubing string; b. a flexIble conduit having an upper end portion and a lower end portion; c. connecting means for connecting the lower end portion of said tubular member to the upper end portion of said flexible conduit to provide communication therebetween; d. a jet treating head having a cavity formed therein and connecting means formed thereon for connecting the lower end portion of said flexible conduit to said jet treating head in communication with the cavity formed therein; e. first nozzle means, formed in said jet treating head and extending outwardly from the cavity therein in a first direction, for ejecting pressurized treating fluid therethrough in the first direction and exerting a first reaction force on said jet treating head in a direction substantially opposite said first direction; f. second nozzle means, formed in said jet treating head and extending outwardly from the cavity in a second direction substantially opposite said first direction of said first nozzle means, for ejecting pressurized treating head in the second direction and exerting a second reaction force on said jet treating head in a direction substantially opposite said second direction, said second reaction force being greater than said first reaction force; and g. means, carried by said tubular member and extending upwardly therefrom, for engaging an external retrieving device, for unseating said tubular member from the seating nipple in response to operation of said retrieving device and for retrieving said tool from the tubing string in response to further operation of said retrieving device.
 2. The retrievable self-decentralized hydra-jet tool as defined in claim 1 characterized further to include: filter means carried by said tubular member for filtering the pressurized treating fluid flowing therethrough from the tubing string into and through said tubular member, flexible conduit, jet treating head and plurality of nozzle means.
 3. The retrievable self-decentralized hydra-jet tool as defined in claim 1 characterized further to include: fluid pressure responsive valve means carried by said tubular member for opening said tool to the flow of pressurized treating fluid through said tubular member, flexible conduit, jet treating head and plurality of nozzle means when the pressure of the treating fluid exceeds a predetermined preset opening pressure and, alternately, closing said tool to said flow of treating fluid therethrough when the pressure of the treating fluid is less than the predetermined preset opening pressure.
 4. A retrievable self-decentralized hydra-jet tool for seating in a seating nipple within and proximate to the lower end of a tubing string in a well bore for use with a source of pressurized treating fluid communicating with the tubing string to control the flow of treating fluid downwardly through the tubing string in response to fluid pressure applied thereto and jet treat the well bore, comprising: a valve body having opposite end portions and a longitudinal passageway extending therethrough and having a fluid flow control port and a valve member actuator port formed therein, each port communicating between the passageway and the outer periphery of said valve body; a valve member slidably disposed within the passageway of said valve body for longitudinal movement therein between a closed position blocking fluid flow between the outer periphery of said valve body and the passageway therethrough and an open position allowing fluid flow between the outer periphery of said valve body and the passageway through the fluid flow control port responsive to fluid pressure acting thereon through the valve member actuator port in said valve body; means formed on said valve body intermediate one end portion thereof and the fluid flow control port for seating the valve body in the seating nipple; means formed on said valve body for providing a fluid-tight seal between the outer periphery of said valve body and the tubing string Intermediate the fluid flow control port and the one end portion thereof; piston means slidably disposed in the passageway adjacent to the opposite end portion of said valve body and longitudinally movable therein in response to the fluid pressure within the tubing string acting thereon; biasing means disposed intermediate said valve member and said piston means for urging said valve member into the closed position in response to the movement of said piston means responsive to the application of fluid pressure to said piston means; a tubular member, having an upper end portion and a lower end portion, connected at its upper end portion to the one end portion of said valve body in communication with the longitudinal passageway therethrough; a flexible conduit, having an upper end portion and a lower end portion, connected at its upper end portion to the lower end portion of said tubular member in communication therewith; a jet treating head having a cavity formed therein and connecting means formed thereon for connecting the lower end portion of said flexible conduit to said jet treating head in communication with the cavity formed therein; and a plurality of nozzle means formed in said jet treating head and extending outwardly from the cavity therein for ejecting pressurized treating fluid therethrough and exerting unbalanced opposite reaction forces on said jet treating head during jet treating of the well bore.
 5. The retrievable self-decentralized hydra-jet tool as defined in claim 4 characterized further to include: filter means disposed within said tubular member intermediate said valve body and said flexible conduit for filtering the pressurized treating fluid flowing therethrough from the valve body and through said tubular member, flexible conduit, jet treating head and nozzle means.
 6. The retrievable self-decentralized hydra-jet tool as defined in claim 4 characterized further to include: means carried by said valve body and engageable with said piston means for limiting the movement of said piston means in response to fluid pressure acting thereon whereby said biasing means urges said valve member into the closed position with a force corresponding to a predetermined valve-opening fluid pressure.
 7. The retrievable self-decentralized hydra-jet tool as defined in claim 6 characterized further to include: means securable to said piston means and responsive to an external force applied thereto for moving said piston means in a direction opposite to the direction of movement thereof responsive to fluid pressure within the tubing string.
 8. The retrievable self-decentralized hydra-jet tool as defined in claim 6 characterized further to include: means securable to said piston means and responsive to an external force for moving said piston means in a direction opposite to the direction of movement thereof responsive to fluid pressure within the tubing string, and unseating said valve body from said seating nipple and retrieving said tool from said tubing string.
 9. A pressure actuated self-decentralized hydra-jet tool for controlling the flow of treating fluid through a conduit in response to fluid pressure within the conduit and for jet treating a well bore in which the conduit is positioned, comprising: a valve body positionable within the conduit, said valve body having an outer periphery, a first end portion and a second end portion, and having a longitudinal passageway extending therethrough and intersecting the first and second end portions; conduit seal means carried by said valve body for sealingly engaging the inner periphery of the conduit proximate the lower end thereof; piston means slidably disposed in the passageway through said valve body adjacent to the second end portion thereof for longitudinal movement within said valve body; retaining means formed on the second end portion of said valve body for retaining said piston means within said valve body; rod meanS connected to said piston means and having the outer end thereof extending through said retaining means for communicating with the fluid in the conduit; limit means secured to the outer end of said rod means for limiting the longitudinal movement of said piston means within said valve body toward the first end portion thereof; means carried by said rod means securable to an external source of power for moving said piston means longitudinally within said valve body toward the second end portion thereof; a valve member slidably disposed within the passageway through said valve body intermediate the first end portion thereof and said piston means, said valve member having an outer periphery, a first end portion positioned proximate to the first end portion of said valve body, a second end portion positioned proximate to said piston means, and a medial portion intermediate said first and second end portions, said valve member having a cavity formed therein and intersecting the first end portion thereof and having a port formed therein communicating between the cavity and the outer periphery of said valve member intermediate the medial portion and the second end portion thereof; a first cylindrically shaped inner surface formed in the passageway of said valve body adjacent to the first end portion of said valve member; a second cylindrically shaped inner surface formed in the passageway of said valve body adjacent to the second end portion of said valve member; a medial cylindrically shaped inner surface formed in the passageway of said valve body intermediate the first and second cylindrically shaped inner surfaces and adjacent to the medial portion of said valve member, said medial cylindrically shaped inner surface having a diameter greater than the diameter of the first cylindrically shaped inner surface and greater than the diameter of the second cylindrically shaped inner surface; first seal means carried by the first end portion of said valve member for providing a sliding seal between the first end portion of said valve member and the first cylindrically shaped inner surface of said valve body; second seal means carried by the second end portion of said valve member for providing a sliding seal between the second end portion of said valve member and the second cylindrically shaped inner surface of said valve body; medial seal means carried by the medial portion of said valve member for providing a sliding seal between the medial portion of said valve member and the medial cylindrically shaped inner surface of said valve body; means carried by said valve body for restricting the sliding movement of said valve member within the passageway of said valve body between a closed position proximate to the first end portion of said valve body and an open position distal from the first end portion of said valve body; biasing means disposed within the passageway through said valve body intermediate the second end portion of said valve member and said piston means for urging said valve member longitudinally away from said piston means into the closed position; a fluid flow control port formed in said valve body and communicating between the outer periphery thereof and the passageway therethrough, said fluid flow control port being positioned in said valve body such that when said valve member is in the closed position said first seal means is positioned longitudinally intermediate said fluid flow control port and the first end portion of said valve body, and when said valve member is in the open position said first seal means is positioned longitudinally intermediate said fluid flow control port and the second end portion of said valve body; a valve member actuating port formed in said valve body and communicating between the outer periphery thereof and the passageway therethrough, said valve member actuating port being positioned in said valve body such that it remains longitudinally intermediate said first seaL means and said medial seal means in all longitudinal positions of said valve member relative to said valve body; a tubular member, having an upper end portion and a lower end portion, connected at the upper end portion thereof to the first end portion of said valve body in communication with the longitudinal passageway therethrough; a flexible conduit, having an upper end portion and a lower end portion, connected at the upper end portion thereof to the lower end portion of said tubular member in communication therewith; a jet treating head, having a cavity formed therein and connecting means carried thereby for connecting the lower end portion of said flexible conduit to said jet treating head in communication with the cavity; and a plurality of nozzle means formed in said jet treating head and extending outwardly from the cavity therein for ejecting pressurized treating fluid therethrough and exerting unbalanced opposite reaction forces on said jet treating head during jet treating of the well bore.
 10. The retrievable self-decentralized hydra-jet tool as defined in claim 9 characterized further to include: filter means disposed within said tubular member intermediate said valve body and said flexible conduit for filtering the treating fluid flowing therethrough from the valve body and through said tubular member, flexible conduit, jet treating head and nozzle means. 